The Lake Kinneret (Sea of Galilee) ecosystem has undergone physical and biological changes over the past 25 years, including a shift from a dinoflagellate Peridinium gatunense)-dominated system to one in which Cyanobacteria play a major role. The Saint Peter’s fish, Sarotherodon galilaeus, the most valuable commercial fish in the lake, was a prime consumer of P. gatunense. Sarotherodon galilaeus has adapted to the ecosystem changes and the scarcity of its primary food source, affecting interactions with other fish in the lake, such as the stocked silver carp, Hypophthalmichthys molitrix. To examine the food habits of the two fish species following the changes in the lake, a total of 300 S. galilaeus and 150 H. molitrix individuals were randomly collected over a five-year period from various places and times in Lake Kinneret. The contents of their stomachs were identified and analyzed. Results showed that a major dietary shift from herbivory to omnivory has occurred since the 1970s in both S. galilaeus and H. molitrix, with H. molitrix now preying almost exclusively on zooplankton. As a result of the dietary changes, both species have had to compete with other fish species for the limited zooplankton resources present in the lake, as well as contending with Cyanobacterial blooms. These changes in the lake’s food web require modifications in the management of the lake and its fisheries.
Bibliographical noteFunding Information:
We would like to thank E. Ophir for his advice and support throughout the course of this research. We are also grateful to the personnel of the Yigal Allon Kinneret Limnological Laboratory for all their assistance. Special thanks are extended to A. Alster-Gloukhovski and T. Zohary for their support in identifying phytoplankton species and to N. Yadlin for sample analyses. We particularly thank M. Lev and the crew of the Ein Gev purse seine for their assistance, advice, and knowledge of fishing. The present study was partially supported by a Sir Maurice and Lady Irene Hatter Research Grant for Maritime Studies to the first author and by a grant from the Ministry of Agriculture and Rural Affairs to Dr. G. Gal.
© 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
- Dietary shift
- Fishery management
- Peridinium gatunense
- Saint Peter’s fish
- Silver carp
ASJC Scopus subject areas
- Aquatic Science